Glue stick



FIG. 1 is a front view of a glue stick according to my design,

FIG. 2 is a rear view thereof;

FIG. 3 is a right side view thereof, the left side view being a mirror image thereof;

FIG. 4 is top view thereof; and,

FIG. 5 is a bottom view thereof. 

The ornamental design for a glue stick, as shown and described. 